Method of treating oil and gas wells



. B. PITZER March 31, 1936.

METHOD OF TREATING OIL AND GAS WELLS Patented Mar. 3l., 1936 METHOD F TBEATING OIL AND GAS WELLS Mose B. lPitzer, Monahans, Tex., asignar of onehalf to Neal M. Huaker, Monahans, Tex.

Application May 17,

6 Claims.

'Ihis invention relates to the methods of producing and treating the porous cavities at the bottom of oil and gas wells, in the oil and gas bearing formation or structure.

The object of the invention resides in the provision of a novel method of treating thevoil and gas formations to increase the production therefrom.

A further object of this invention resides in the provision of various materials for carrying out the methods of treating oil and gas wells or formations thereof, as hereinafter described more fully.

A still further object resides in the provision of a novel method of applying the various materials to the oil and gas bearing formation in such Way as to create a porous cavity formation, thereby to secure the maximum production from the various formations in oil and gas wells and -the like; and in the use of materials which will assure the proper and desired results, and which will not become gas cut.

Another object is to apply various materials to the oil and gas formations or structures, or cavities thereof, under pressure and to employ materials which will not reduce the gas pressure or corrode the drill pipe or -tubing thereof.

A further object is to apply the treatment materials to very soft or floating sand formations, where it has been heretofore impossible to produce and retain a. porous cavity formation, a1- though they can be used as well in other formations. e It is well known to those skilled in the art that in all oil and gas bearing 4sand and sandy-lime or lime formations the operator does not secure the maximum production. This has been due generally to the fact that it has not been possible to produce and maintain a large cavity of porous formation in the oil and gas structure or formation, because the sand or soft sandy-lime or lime formation, isconstantly shifting and filling the cavity, so that it is necessary not only to frequently clean out the Well at the bottom or in the oil and gas formation, but also results in reduced production therefrom, as well as loss of time due to the cleaning out opsration.

It is an object of the present invention to produce and so treat the walls of theformed porous cavity in the oil and gas bearing structure as to prevent the materials of the Walls from shifting without, however, reducing. the porosity of the cavity walls.

It is a further object of the invention to use in the treatment of oil and gas wells and the 1935, Serial No. 22,081 (Cl. 166-21) like, materials which will not only produce the results already stated, but will serve as nonconductors of electricity, so that corrosion of the well casing or drill pipe from electrolytic ac` tion will not occur.

A further object is to employ treatment material which will not absorb or reduce the gas pressure.

Other objects and advantages are found in certain novel steps of the method and in the various materials used, as well as in the arrangements and combinations of the treatment materials, as will be hereinafter more fully described and pointed out in the following specifications.

With the foregoing and other objects in view the invention consists of certain novel steps of the methods hereinafter described, it being understood that changes may be made herein within the scope of the appended claims.

In carrying out the method the well is drilled in the usual marmerafter which a porous cavity of desired size is formed at the bottom thereof in the producing formation. The porous cavity can be secured in some formations bythe use of an under-reamer. In some formations satisfactory results can be obtained by shooting the formation of the well. In various other formations the porous cavity can be produced by the use of various compounds, such as acids, alkaliesv or other chemicals, either mixed, diluted or otherwise, all of which depends entirely upon the structure encountered in the well or producing formation.

Some of the various chemicals which may be. used in a sand, sand-stone, lime, limestone or shale formation to produce the porous cavity are nitric, sulphuric, hydrofluoric, hydrochloric and muriaticacids, or' various chemical compounds', such as chlorides, salts or alkalies, either mixed or otherwise, that will produce the Vdesired results. 40 Also steam or gas under pressure or any other means might be used.

As before stated, in all sand and some soft-lime, and in a oating sand, or in a lime formation, it is practically impossible to maintain a porous cavity at a predetermined size because the-materials of its walls will shift. It has been found that by ,using certain'materials as a binder, the sand or soft sandy-lime or lime forming the walls of the cavity can be held in place without rcducing the porous nature of the cavity walls, and at the same time securing a larger area of porous cavity formation from which to produce. The materials used for this purpose preferably consist of barium sulphate or barytes crushed to 1 55 to 11/2 inch mesh. Other materials such as limestone, quartz, and the like crushed to the same size may also be used under some conditions, it being essential usually that the materials employed have a specific gravity in excess of 2.

Of the crushed materials which may be used barium sulphate or barytes having a specic gravity of from 4.3 to 4.6 is most desirable because it is chemically inert and is a non-conductor of electric currents, and is not easily cut by gas.

After the porous cavity has been produced at the bottom of the well in the oil and gas formation and the like, a suiiicient amount of the crushed treatment material is deposited in the well to ll the cavity or a portion thereof. By means of a fiat or U-shaped drill bit, or by other forcing means, the treatment material thus deposited is forced back into the cavity walls, or the material can be forced back into the cavity walls by dropping the tools thereon, or by the use of a small shot of nitroglycerine. As a result of this action the treatment material will be displaced radially and downwardly from the cavity and will be forced back into the sand or soft lime formation so as to form walls made up of an intimate mixture of treatment material and sand, lime or shale.

The barium sulphate or other crushed materials employed will act as a binder without reducing the porosity of the Vcavity walls in the oil and gas structure.

Should one operation such as described beinsufilcient to meet the requirements, additional crushed treatment material can be deposited in the cavity and forced back into the walls thereof as before.

Under some conditions it will be found necessary to use two or more tons of crushed barium sulphate in order to complete the operation. I

If desired, any of the treatment material which may be left free within the cavity following the completion of the operation can be removed readily by bailing it out of the well.

Should the bottom of the well be excessively soft, the treatment of the walls of the cavity can be facilitated by covering the bottom surface lwith a plug of concrete. After the concrete has set, the treatment material is deposited in the cavity and forced back into the walls of the cavity as before described.

The concrete base will prevent the material from being discharged downwardly in the bottom surface of the well. It will, instead, deflect all of the crushed material radially into the walls of the cavity.

After the cavity has been treated as described and the porous formation secured, the well can be connected up inV the usual manner and production proceeded with.

It has been found-that, by packing the treatment material back into the walls of the cavity,

the sand or sandy-lime formationV in which the cavity is located will not crawl or become displaced. On the contrary the sizeof the cavity will be maintained and frequent cleaning out operations will be avoided. Consequently maximum production 'takes place.`

As before stated barium sulphate or barytes is an inert substance which will not conduct electric current. Consequently where this crushed material is used in the treatment of the cavity walls there will be no corrosion of metalparts, such as the well casing or drill pipe, due to electrolytic action. FurthermoreA as the barytes will not absorb gas pressure or react upon the gas in any way, better results are obtained than should any other material, such as iron oxide, be employed as a crushed treatment material.

It is to be understood that the crushed treatment material should not be smaller than one inch mesh. Any finer crushed materials if applied as herein stated would reduce the porosity of the cavity Walls and would thus be objectionable.

When a crushed material of the size herein described is used it retains the porous Walls and at the same time holds the walls Ain shape.

In the accompanying drawing there has been illustrated rthe seyeral stepsin the described method.

Iny said drawing Figure 1 is a section through the lower portion of a drilled Well prior to the enlargement of its lower end.

Figure 2 is a similar view showing a cavity which has been formed in the bottom of the well in the oil and gas formation by under-reaming or by any other means.

Figure 3 shows the cavity filled with crushed treatment material such as barium sulphate, prior to the forcing of the material into the cavity walls.

Figure 4 is a view similar to Figure 3 showing the crushed treatment material after it has been forced into the walls ofthe cavity.

Figure 5 is a view similar to Figure 3 showin a moded method utilizing a bottom plug of concrete, the cavity being shown lled prior to the forcing operation.v

In the drawing, I designates the well, 2 the cavity, and 3 the treatment material.

A drill bit used for forcing the' crushedtreatment material into the walls of the cavity has been indicated at 5, and in Figure 4 the crushed treatment material has been shown commingled with the sand, soft limestone or shale making up the original walls of the cavity.

After the bit 5 has been withdrawnl the packed walls will retain their shape without crawling or shifting.

In Figure 5 the concrete plug used as a support for the crushed treatment material in the cavity has been indicated at 6, the crushed treatment material 3, being shown within the cavity prior to being forced outwardly into the Walls thereof.

The treatment material when forced into the interior of the cavity walls in the oil and gas formation produces a porous sand or sandy lime formation and will assure the maximum production from the oil and gas bearing structure.

If so desired, after some of the crushed material has been forced into the walls of the cavity, the remainder may be left within the hole up to thel casing or tubing. This depends entirely upon the formation or structure encountered.

Obviously in some soft formations the crushed Amaterials herein, referred to may be employed to secure or retain the walls of the hole so as to prevent them from shifting Aand preventing the drill bit from becominglodged while the drilling operation is in progress.

Iny some soft sand or other formations, such as a floating sand, where it is impossible to secure a cavity so that the crushed materials may be applied, the crushed material may be deposited in the bottom of the well and then a charge of hydroiiuoric acid or other chemicals or alkalies or compounds, may be applied or forced into the well, where it will seep into the soft sand or sandy lime formation through the porous crushed materials, and as the reaction takes place the crushed material will seek its level in the soft or floating sand formation, and then can be forced back into the formations. As before stated barytes is chemically inert and is only three percent soluble in hydrochloric and other acids Yor chemicals. Therefore this application can be effected with safety.

After the desired amount of the crushed ma-,

terials has been applied the Well can be connected up for producing in the usual manner.

It is to be understood that most chemicals, acids, compounds and alkalies are more effective when applied to various formations in a heated condition and under pressure. In some sand formations hot alkalies are very effective.

It is also to be understood that one of the main objects is to use broken materials which Will not crush flat or smooth, but instead,when crushed, will retain rough surfaces, so that the particles Will not pack together when applied to the oil and gas formation as herein stated, but, instead, will maintainv a porous formation when forced back into the oil and gas structure.

What is claimed is:

1. The herein described method of treating sand or soft lime or limestone formations in the bottoms of oil wells and the like which includes the step of producing a cavity at the bottom of the well in the producing formation, placing in the cavity an inert crushed treatment material of substantially from 1 to 1 A inch mesh, and pounding said crushed material to displace it from the cavity and to force it into the walls of said cavity to form an intimate mixture with the original materials of the Walls to produce a porous formation.

2. The herein described method of treating a sand, floating sand, lime, limestone or shale formation in the bottoms of oil wells and the like which includes the step of producing a porous cavity at the bottom of the Well, lling the cavity with barium sulphate of substantially 1 to ll/g inch mesh, and pounding. said crushed barium sulphate to displace it from the cavity and forceit into the walls of said cavity to form an intimate mixture with the original material of the walls to produce a porous formation.

3. The method of treating sand, lime, or limestone formations in oil and gas wells which includes the steps of rst producing a porous cavity at the bottom of the well, thereafter forming a hard plastic coating on the bottom of the cavity, then lling the cavity above said coating with a crushed treatment material of approximately from 1 to 11/2 inch mesh, said material being inert and a non-conductor of electricity, andsubsequently pounding said crushed material to displace the greater portion thereof from within the cavity and pack it into the walls of the cavity to form an intimate mixture with the original materials of the walls and produce a porous formation.

4. The herein described method of treating sand, sandstone, lime, limestone and shale formations in the bottoms of oil and gas wells and the like, in the oil andgas bearing structure, which includes the step of applying treatment materials of the class described tothe oil and gas bearing structure so as to produce a porous cavity formation in the oil and gas bearing structure, and placing in said cavity crushed treatment materials that will not corrode the drill pipe or tubing, said materials being chemically inert and non-conductors of electricity and having a specific gravity in excess of 2, thereby to retain the porous cavity walls and then pounding the greater portion of the material out of the cavity and back into .the formation thereby to produce porous cavity walls.

5. The method of treating sand or soft limestone formations in oil or gas wells which includes the steps of first producing a cavity at the bottom of the well, thereafter forming a. hard plastic coating on the bottom of the cavity, then placing in the cavity above said coating a solid treatment material of approximately 11/2 inch mesh, said material being inert and a non-conductor of electricity and subsequentlyv pounding said material to displace it within the cavity and pack it into the walls of the cavity to form an intimate mixture with th original material of the Walls.

6. The herein described method of treating a sand, floating sand, lime, limestone or shale formation in oil wells and the like which includes the steps of drilling the well and placing therein an inert crushed treatment material of substantially from., 1 to 11/2 `inch mesh, and pounding said crushed material to displace it into the wall of the well to form an intimate mixture with the original materials of the wall and produce a porous formation.

MOSE B. PITZER. 

